Thermostat with aspirated air



Feb. l, 1966 w. P. WEHLAU 3,232,112

THERMOSTAT WITH ASPIRATED AIR Filed Oct. 28, 1963 2 Sheets-Sheet l Feb., 1, 1966 w. P. WEHLAU THERMOSTAT WITH ASPIRATED AIR 2 Sheets-Sheet 2 Filed 0G12. 28, 1963 United States Patent ilice 3,232,112 THERMOSTAT WITH ASPIRA'IED AKR William P. Wehl'au, Niles, Ill., assignor to The Powers Regulator Company, Skokie, lll., a corporation of Illinois Filed Oct. 28, 1963, Ser. No. 319,177

3 Claims. (Cl. 73-349) This invention relates in general to thermostatic temperature regulation in enclosed gaseous environs such as dwellings and the like. It deals more particularly with apparatus forvimproving the performance of a tem-- perature regulating thermostat.

It is common practice to control the temperature in a dwelling, for example, or any enclosure, by means of a temperature sensing thermostat which is effective to ad* just a heating or cooling supply of hot or cold air to the enclosure as a function of thetemperature therein. One widely used type of thermostatic device employs an air pressure control system which is sensitive to variations in temperature within the enclosure. A control pressure increases or decreases with a rise or drop in ambient air temperature and provides an indication, according to `a predetermined schedule, of the air temperature inthe Adevice to such a representative sampling of air in a room, for example, at all times.

It is another object of the present invention to provide a new and improved aspirator arrangement for directing Vambient'air from an enclosure across temperature lsensing equipment in a thermostat, in a predetermined manner.

It is still another object to provide an aspirator arrange- 'rnent which is especially suited .for directing ambient air across the sensing equipment of athermostatjin an enclosed `and recessed `wall box.

It is yet another object to provide an aspirator arrangement of the aforedescribed character which facilitates line adjustment to suit aircirculation conditions and provide the most sensitive temperature response possible.

lt is a further object to provide an aspirator arrangement of the aforedescribed characterwhich draws aspirating air from the air pressure control system of the thermostatic device. i

The foregoing and other objects are realized in accordance lwith-the present inventionby lproviding a new and improved aspirator apparatus for circulating ambient air or the likevin a predetermined manner over the temperature sensitive control equipment of a thermostat employing an air pressure control system. vArnbientrair is drawn into arecessed wall enclosure, for example, containing the thermostat, at'a predetermined rate and directed across its temperature sensitive equipment by a controlled jet of air bled from the air pressure control systemof the thermostat. The rate of passage of ambient air is adjusted by varying the air bleed rate Afrom the air pres- .sure control system. Adjusting ,the rate of ambient air flow facilitates metering it .past the temperature sensing Patented Feb. 1, 1966 equipment just fast enough for quick and accurate thermostatic response without effecting Vfalse response.

The invention, both as .to its organization and VI nethod of operation,rtaken with further objects andadvantages thereof, will best be understood by reference to the following description taken in conjunction with the, accompanying drawings, in which:

FIGURE 1 is a perspective view of Va thermostatic device incorporating an aspirator arrangement embodying features of the present invention, set in the wall of ,a dwelling room, for example, with parts broken away;

FIGURE 2 isA an enlarged front elevational view of the thermostatic device illustrated in FIGURE 1, ,with` its cover removed to display a thermostat ofthe type employing an air pressure controlvsystem and incorporating features yof the present invention;

FIGURE 3A is a sectional fview taken along line 3 3 of FIGURE 2, with the cover in place;

FIGURE 4 is a rear perspective View of the thermostat separated from the housing in FIGURE 2;

FIGURE 5 is an enlarged sectionalviewof a portio of the ambient air egress port means embodying yfeatures of the present invention; and

FIGURE 6 is an enlarged view taken along line `6-6 of FIGURE 3.

Referring now to the drawings, and particularly to FIGURE l, a thermostat package 10 is shown seated in recessed relationship in the wall 11 .of a conventional dwelling or the like. The thermostat package 10 is operatively connected in a well known manner to a heating and/ or cooling system (not shown) whereby the heating and/or cooling ofthe room is controlled bythe thermostat package 10 to maintain a predetermined ambient temperature in the room. Ambient temperature in the room is continually sensed by the thermostat package according to features lof the present inventionand the heating and/or cooling of lthe room controlled as a direct function of such sensed temperatures.

The thermostat package 10 is illustrated in greater detail in FIGURES 24. There it will be Vseen that the package 10 includesfathermostat 15 mounted within the confines of a recessed wall housing 15 and operated :by air pressure. The thermostatlwhich in detail forms no part of the present invention, is in this case ga direct acting thermostat which utilizes air :pressure'to control a mixing damper (-not shown) supplying, hot or cold air to a room or the like.

The direct acting thermostat 15 increases control Yair pressure with a rise in ambient air temperature and decreases control air `pressure with a drop in ambient air temperature. The control air pressureis, infturn, preferably connecteddirectly tothe damper motor (not shown) of a mixing damper for controllingthe position .of hot and cold-blades (not shown). Thus, with an increase in room ltemperature the thermostat 15 increases the control pressure to the damper motor to close the hot blade and open the cold blade while, conversely, with a drop in room temperature the thermostat 15 reduces the control pressure to close the cold land open the hot blade. T-he ,mixing damper is preset in advance to provide a flow of air of predetermined optimum temperature, of course, fora predetermined pressure setting .indicative of the selected temperature.

The thermostat 15 is connected to a source of air 20, under a pressure of in the neighborhood of about 20 p.s.i.,

' sure from the source 20 to the damper control 23.

through a supply pipe 21. The thermostat meters the tflow of this air under pressure from the source 20, through .Ian exhaust pipe 22, to the damper control, seen diagramv which react to changes in temperature in the ambient air surrounding them to control the metered flow of air pres- In `the thermostat 15 illustrated, which is manufactured and sold by Powers Regulator Company, assignee of the present invention, a sensitivity of about 2.5 p.s.i. per degree Fahrenheit change in ambient temperature is realized.

' To set the thermostat 15 at a predetermined temperature, l a temperature set wheel is manipulated to bring a premeter a neutral air pressure to the damper control 23,

ten p.s.i. for example, is thus Varied.

It is important, of course, that a representative sampling of the ambient air in the room which is having its temperature controlled be in surrounding relationship with the thermostatic discs 30 and 31. With the thermostat 15 recessed in a wall housing 16, for example, this end is not always readily effected. In fact, it is not uncommon for .'air within such a housing 16 to become stagnated, almost insulating the discs 30 and 31, and tending to cause indications of higher temperatures than actually exist within the room. The constant, yet regulated slow flow of ambient air across the thermostatic disc 30 and 31, according to the present invention, is an advantageous departure from such an arrangement.

According to the present invention, an aspirator arrangement 40 accomplishes this end by providing a steady but regulated flow of ambient air across the thermostatic discs 30 and 31. The aspirator arrangement 40 draws air under pressure from the air pressure system of the thermostat 15 and directs it at a controlled, adjustable rate out of the housing 16. The effect of this controlled egress of air from the housing 16 is to draw ambient air into the housing 16- and lover the thermostatic discs 30 and 31 at a predetermined rate.

The aspirator arrangement 40 includes an air jet assembly 41 which is interposed in the supply pipe 21 supplying air under pressure to the thermostat 15, as best seen in FIGURE 2. The air jet assembly 41 includes a 'I fitting 42 secured in the conduit 21 by conventional threaded couplings 43. The T fitting 42 includes an outwardly extending short pipe leg 45 into which an aspirator head 46 is fitted in any well known manner. A small air passage 41 extends through the aspirator 46 from lthe pipe leg 45 to a nozzle assembly 48. An adjustable needle Valve 49 in the aspirator 'head 46 facilitates control of the ow of air through the passage 47 and, accordingly, to the nozzle assembly 48.

The nozzle. assembly 48 includes a threaded fitting Sil which screws into the aspirator head 46 in communication with the passage 47, and a jet 51 extending at right angles from the fitting. The jet 51 is pointed upwardly, asv/ill be noted, parallel to the Vertical axis of the thermostat 15 and the cover 55 of the housing 16.

The cover 55 comprises a rectangular plate 56 which overlies inwardly turned anges 57 of the housing 16 and is secured thereto in any suitable manner, as byl screws 56d. As best seen in FIGURE l, the cover 55 contains a horizontally disposed, vertically displaced pair of air inlet slots 53 and 59 which provide access to the housing for amibent air, and a horizontally disposed, vertically displaced pair of egress slots 61a and 61h. According to d. the present invention, 'the egress, slots 61a ,and 61h are modified to assure dptimum desirable ambient air flow through the husing 16.

The jt assembly 41 is adapted to direct a stream of air underneath the cover 55, within the confines of the housing 16, to cause ambient air to be drawn in the access slots 58 and 59 and forced out of the modified egress slots 61a and 61h. The egress slots 61a and 61h are modified by providing a wedge shaped enclosure 66 mounted on the inner side of the plate in the manner illustrated in FIGURES 3, 5, and 6.

The enclosure 66 includes oppositely disposed wedgeshaped walls 66a and a generally rectangular roof 62. The walls 60a and one rend 6?; of the roof 6,2 are 'secured to the inner side of the cyi A55, preferably by welding cir the like. n Fornin'g a partial tlr on the ramped housing 60 is a floor section 65. The oor section overlies the lower egress slot 61h and has a knife-like inclined edge 66 extending out over the upper egress slot 61a. The flat edge 66 and the roof 62 forms a diverging downstream throat portion between the oor section 65 and the cover 62 while the door section 65 upstream of said edge 66 forms a converging throat portion with the roof.

The aforedescrioed `construction and arrangement of the ramped housing 60 leaves only a narrow slit 70 for the egress of air from the housing 16. Accordingly, when air from the nozzle 51 is forced through the slit 70 it creates, by Venturi effect, a slight vacuum within the housing 16, causing ambient air to be drawn in the access ports 58 and 59. The ambient air circulates around the there mostat discs 30 and 31 until it, too is directed out of the slit by the jet of air from the nozzle 51, In this 'mariner, a constant flow of ambient air across Ithe thermostatic discs 36 and 31 is maintained and accurate temperature response of the thermostat 15 assured. The'knife edge 66 prevents air fiow disturbance in the departing air.

The present invention is especially valuable in that the standard thermostats 15 and the thermostat housing covers 55 can easily be modified to incorporate the as= pirator arrangement embodying features of the present invention. By merely mounting the 'ramped housing 60, as hereinbefore described, on the inner side of the cover 55 and inserting the jet assembly 41 inthe supply pipe 21, an aspirated thermostat according fo the present invention is provided.

While the embodiment described herein is at present considered to be preferred, it is understood that various modifications and improvements may be made therein, and it is intended to cover in the appended claims all such modifications and improvements as fall within the true spirit and scope of the invention.

What is desired to be vclaimed by Letters Patent of the United States is:

1. In a thermostatic system including a temperature sensitive thermostat mounted within a substantially closed housing, and a source of air underV pressure, the improvement comprising: cover plate means on said housing, access port means in said cover plate means for ambient air to enter the housing, egress slot means in said cover plate means for air to depart the housing, jet means in said housing for directing a jet of air under said cover plate means in the direction of said egress slot means, enclosure means inside said housing overlying said slot means, said enclosure means defining a throat over said slot means which initially narrows in cross sectional dimension and subsequently increases in cross sectional dimensions whereby air forced through said throat by said jet of air creates a venturi effect to reduce pressure in the housing and draw ambient air into the housing through said access port means.

5 6 floor secured to said cover plate, the downstream end References Cited by the Examiner of said lloor having a knife edge formed thereon, the UNITED STATES PATENTS floor and said roof upstream of said knife edge means dening the initial narrowing portion of said throat, and 713,496 11/1902 Root 230 111 X the knife edge portion and said roof dening the subse- 5 216209 83 12/1952 Lyman 236`13 quent widening portion of said throat. 2,919,068 12/1959 Kautz 236-'13 3. The improvement in thermostatic system of claim 2 further characterized in that -said jet means directs said FOREIGN PTENTS jet of air parallel to said cover plate into angular im- 163,906 7/1955 AUSlaha.

pingement on said roof upstream of the narrowest point 10 l l in Said throat ALDEN D. STEWART, Przmary Examzner. 

1. IN A THERMOSTATIC SYSTEM INCLUDING A TEMPERATURE SENSITIVE THERMOSTAT MOUNTED WITHIN A SUBSTANTIALLY CLOSED HOUSING, AND A SOURCE OF AIR UNDER PRESSURE, THE IMPROVEMENT COMPRISING: COVER PLATE MEANS ON SAID HOUSING, ACCESS PORT MEANS IN SAID COVER PLATE MEANS FOR AMBIENT AIR TO ENTER THE HOUSING, EGRESS SLOT MEANS IN SAID COVER PLATE MEANS FOR AIR TO DEPART THE HOUSING, JET MEANS IN SAID HOUSING FOR DIRECTING A JET OF AIR UNDER SAID COVER PLATE MEANS IN THE DIRECTION OF SAID EGRESS SLOT MEANS, ENCLOSURE MEANS INSIDE SAID HOUSING OVERLYING SAID SLOT MEANS, SAID ENCLOSURE MEANS DEFINING A THROAT OVER SAID SLOT MEANS WHICH INITIALLY NARROWS IN CROSS SECTIONAL DIMENSION AND SUBSEQUENTLY INCREASES IN CROSS SECTIONAL DIMENSIONS WHEREBY AIR FORCED THROUGH SAID THROAT BY SAID JET OF AIR CREATES A VENTURI EFFECT TO REDUCE PRESSURE IN THE HOUSING AND DRAW AMBIENT AIR INTO THE HOUSING THROUGH SAID ACCESS PORT MEANS. 